fix the bad formating in README
launch a repairDatabase task on clear_resolved

The task db:clear_resolved can delete a lot of data. I think it can be good to repairDatabase after to avoid a big database.

see #458
Extract task to clear problem resolved in Interaction class

Extract the task in a class doing the job
Add test on this class
Update rspec and rspec-rails gems
Merge pull request #468 from shingara/patch-1

launch a repairDatabase task on clear_resolved